GPS (global positioning systems) have become ubiquitous in today's passenger vehicles. They are used for helping the driver navigate to a destination and do not have very high accuracy. Satellite reception in various urban settings can be sporadic and can result in loss of signal periodically. High accurate GPS is a very critical feedback in autonomous ground vehicles.
Unmanned urban ground vehicles (UGV's) are robotic platforms that are either remotely operated or autonomous. They are generally capable of operating outdoors and over a wide variety of terrain.
An autonomous UGV is essentially an autonomous robot with mechanisms that allow it to navigate on the surface of the ground. Among other tasks, a fully autonomous robot in the real world has the ability to travel without human navigation assistance.
One approach to the autonomous navigation problem is referred to as the Simultaneous Localization and Mapping (SLAM) approach. In the SLAM approach, the true world location of landmarks or of the vehicle itself is not needed. The basic operating methods of SLAM are the ability to place an autonomous vehicle at an unknown location in an unknown environment, have it build a map, using only relative observations of the environment, and then use this map to navigate. The main advantage of SLAM is that it eliminates the need for a priori topological knowledge of the environment. A solution to the SLAM problem is valuable in applications where absolute position or information is unobtainable.
Another approach to autonomous navigation uses GPS data. If GPS data is available to the vehicle, the vehicle can acquire GPS data live to determine its location. Alternatively, for environments where GPS data is not available, with the advent of advanced mapping information from companies such as Google, Yahoo and Microsoft, a priori knowledge of GPS coordinates of landmarks can be stored before driving a route. Based on perception technologies such as machine vision or LIDAR, and intelligent processing, landmarks can be identified en route. The vehicle determines its position based on GPS coordinates for the landmarks. Generally, once each current location is known, the vehicle can then navigate to a next location.